This invention relates to improvements in material handling apparatus and, more particularly, to a mechanism for pushing and diverting objects from conveyors.
It is well known in the prior art of material handling to employ conveyors with moving belts or the like for transporting objects of various sizes and shapes along a path. It is also common practice to utilize diverters along the path for transferring, sorting or distributing the objects at certain points to other locations such as auxiliary conveyors, spurs or outflow chutes. Such arrangements have particular utility in warehouses, factories, truck terminals, shipping rooms, mail bag and courier distribution and airline baggage systems. In these applications, the diverters may individually, or in combination, push an object at some angle across a conveyor belt, block an object at some angle to the belt so that the belt motion causes the object to slide across the belt, or arrest the motion of and snatch the object from the belt. Additionally, the diverters may employ linear, translatory, or rotary movement of one or more object engaging devices which move through forward and return cycles to unload or remove objects form the belt.
For example, U.S. Pat. No. 3,198,308 to Driesch et all discloses a linear pusher having a paddle fixed at the end of a reciprocating piston rod and parallel to the conveyor belt. Driesch et all also disclose a snatcher having a paddle pivotally attached at one end of a framework and at its end portion to the end of a reciprocating piston rod.
U.S. Pat. No. 3,026,988 to Fisk and U.S. Pat. No. 4,295,559 to Neal et al are illustrative of air-actuated translatory linkages used to move together with an article along the conveyor while simultaneously shifting the article transversely of the conveyor.
U.S. Pat. No. 3,083,808 to Graybeal and U.S. Pat. No. 4,441,604 to Schlig et al disclose rotary pushers wherein dual paddles are revolved in a rotary motion to engage objects such that the face of each paddle will always remain parallel to the direction of belt travel.
Various attempts have been made by each of these patents to upgrade sorting or orienting capability of objects at high speeds by provision of different paddle linkages and their associated drives along with the ensuing geometric motion produced thereby. However, there remains a need in this well-developed art for a diverting pusher which is capable of accomplishing transfer of objects at high rates by controlling the motion and speed of the paddle on a push phase of a cycle for gentle object handling, and then performing the remainder of the cycle rapidly to maximize cycle rate and reduce the spacing between conveyed objects.
For instance, when utilizing some prior art devices, some paddles may dwell too long at the end of their forward stroke or operate with time delays which can create jams and missorts. In other cases, the moving mass of the paddle may be at maximum velocity at time of impact with the object with resultant damage or destruction to the objects. These are particularly sensitive drawbacks when diverters or pushers are used in the handling of airline baggage which may vary tremendously in size, shape and fragility.
As will be seen hereinafter, it is a principal object of the invention to provide an improved pushing and diverting mechanism for unloading a wide variety of objects from a conveyor at a high rate of speed with accuracy and control.